CVE-2026-121528: High severity vulnerability
A improper certificate validation vulnerability in Fortinet FortiOS 7.6.0 through 7.6.4, FortiOS 7.4.0 through 7.4.9, FortiOS 7.2.0 through 7.2.13 may allow a remote and unauthenticated attacker to perform a Man-in-the-Middle attack on the communication channel between the SSLVPN web portal and the backend destination website.
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Fortinet FortiOSto a version that resolves this vulnerability.Fixed in 7.2.14 - Upgrade
Upgrade
Fortinet FortiOSto a version that resolves this vulnerability.Fixed in 7.4.10 - Upgrade
Upgrade
Fortinet FortiOSto a version that resolves this vulnerability.Fixed in 7.6.5 - Upgrade
Upgrade
Fortinet FortiOSto a version that resolves this vulnerability.Fixed in 8.0.0
Event History
Frequently Asked Questions
Which deployments are exposed to this issue?
FortiOS 7.6.0 through 7.6.4, 7.4.0 through 7.4.9, and 7.2.0 through 7.2.13 are affected when the SSLVPN web portal communicates with a backend destination website.
Does an attacker need credentials or user interaction to exploit this?
No. The issue may be exploited by a remote, unauthenticated attacker, and the supplied vector indicates no user interaction is required.
What could an attacker achieve through exploitation?
An attacker may perform a man-in-the-middle attack on the communication channel between the SSLVPN web portal and the backend destination website. The provided severity vector rates confidentiality, integrity, and availability impact as high.